“How can I test my dog's eyesight?”

If your dog is running into things, that can definitely be the first sign. Also, not if they are running into things just at night or during the night and day. If just the night, your dog may possibly have night blindness. Otherwise, there are a couple of tests you can do at home which may help determine if your dog is blind. The menace test is where you swiftly move you hand near the corners of their eyes and see if they blink (without touching fur, etc). If they don't blink, this could be a sign that your dog is blind. Another test is the pupillary light reflex. In a dim room, shine a flashlight (this can be your phone's flashlight too) into their eye and see if their pupil becomes smaller immediately. If it doesn't, this can also indicate that your dog is blind. Another thing you can do is take an object and see if they can follow it with their eyes.